1. Pre­heat oven to 170C or 150C fan and line 12 medium muf­fin tins with pa­per cases. Place flour into a large mix­ing bowl. Stir in co­conut and sugar and make a well in the cen­tre. 2. Use a fork to whisk eggs, co­conut milk and lemon zest in a jug. Add to the dry in­gre­di­ents, along with the but­ter. Fold to­gether un­til just com­bined but don't mix or beat. Spoon into pre­pared cases. Bake for 20 mins, or un­til springy to a light touch. Leave in the tin for 5 mins then lift out onto a wire rack to cool. 3. To make the ic­ing, sift ic­ing sugar into a bowl and add but­ter. Pour boil­ing water onto but­ter to melt it and stir un­til smooth. Spread over each cake, sprin­kle with co­conut flakes and leave to set.